The National Hurricane Center began talking about the maps last year as part of an effort to improve the way forecasters talk about the abnormal rise of sea water during hurricanes. Many factors contribute to storm surge, and predictions about the potential flooding sometimes caused confusion.

The new maps will show where storm surge could happen and how high the water could rise in those areas. They will be issued when a hurricane or tropical storm watch is first posted for any part of the Gulf or East coasts, 48 hours before tropical storm-force winds are expected. Then they’ll be updated every six hours throughout the storm.